[TowerTalk] Takeoff angles HF VS VHF / F2 VS Es DE K0FF

[K0FF]

Lets talk apples to apples and oranges to oranges or the newbies will get
totally confused. On F2 skip, which is the predominate mode on HF a low
angle is almost always better than a high angle for long distance
communication. I can demonstrate this clearly in my own shack on 20M any
time with the 2 different 20M beams. For stateside daytime operations like
nets or ragchewing, the Mosley Pro57 set at 50 or 60 feet is the preferred
antenna. For long haul stuff at dusk, the 5 el monobander at 100+ feet can
hear and work stations in Asia over the pole that the Mosley wont even
detect. Time after time, day after day.  Same rig, both antennas on a
switch.

On Es skip, it's a different matter. This applies to 6M as well as 10 M in
the summertime. Thousands of tests have shown that a low mounted high gain
antenna tilted up (or just low mounted, as the angle is automatically
increased with diminishing height) is as good a performer or better than a
high antenna with it's low angle.  Es skip arrives at a higher angle than F
skip does by a large factor. I have found that on long haul 6M DX (Central
Europe from Missouri) that this is still true even though the first hop is
about as long as it can possibly be on Es (1400 miles or so). On other paths
from here, say far South America, or even VK/ZL, the path is more
complicated in that a link between a pure Es hop at my end into one or
anther type of F intermediate occurs, but nonetheless, my end is Es and
responds better to a higher angle. As soon as the first hop is via an F
layer, this all changes, and all the usual HF rules apply.

Another closely related hobby TV DXing using a similar approach. The
antennas are purposely mounted low
(15 feet), and turned vertical. This block most of the "groundwave" or Tropo
signals because of the cross polarity ( On skywave, Faraday rotation pretty
much does away with the original polarity). Then the antenna is tilted up by
10 degrees to enhance it's performance to the incoming wave. AGAIN this is
Es and not F.

As far as the "increasing number of full elevation EME stations on 6M", I
guess there are more now than ever, but I see only 9 stations listed as
being EME active (on the ARRL Webpage), and I know for a fact that some of
those do NOT have elevation control (horizon shots only).

By the way on the subject of 6M EME, it may well be better NOT to use
elevation control, because when aimed above the horizon, "ground gain" is
lost, and the path is so marginal anyway that the loss of   any gain makes
it that much more difficult.


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